1. Field of the Invention
The present invention relates to a developing method for developing electrostatic latent images in electrophotography and electrostatic printing, and more specifically to a mono-component developing method using a mono-component developing agent.
2. Description of the Related Art
In the mono-component developing method, since toner passes between the developing sleeve and the developer-regulating blade to be charged electrically, a great stress is applied to the toner. This stress causes embedment of post-treating agents and toner cracking and the subsequent generation of smaller-size particles, resulting in adhesion of the toner component to the developer-regulating blade. The resulting problems are insufficient charging due to degradation in the toner-thin-layer forming capability, filming due to fused toner component onto the sleeve and fog on the photosensitive member, thereby failing to provide a good developing process.
In order to solve these problems, techniques for conglobating the shape of toner have been developed in recent years. The conglobation of toner minimizes the toner cracking due to the stress, reduces the occurrence of smaller-size particles, and reduces sleeve filming, etc.
More specifically, there have been proposed a method for preparing spherical toner by using a suspension polymerization method and an emulsion polymerization method in a wet system (Japanese Patent Application Laid-Open No. Hei 1-257857(1989) and techniques for conglobating toner by thermally treating pulverized toner (Japanese Patent Publication No. Hei 4-27897(1992) (Japanese Patent Application Laid-Open No. Hei 6-317928(1994).
However, the conglobation of toner shape reduces toner powder pressure at the contact section with the developer-regulating blade, resulting in a new problem of insufficient toner transferability due to insufficient toner passage between the developer-transferring and supporting member and the developer-regulating blade.
An attempt has been made to provide a certain degree of irregularity to the developer-transferring and supporting member so as to improve the transferring properties. However, the conventional conglobated toner fails to provide sufficient durability and charging stability. In particular, in the case of high transferring speeds of the developer sleeve for high speed systems, the conventional conglobated toner causes filming due to fused toner onto the surface of the sleeve and fog on the photosensitive member, resulting in degradation in durability and charging stability.